Determination of the karyotype of the giant anteater Myrmecophaga tridactyla (Myrmecophagidae: Xenarthra) using classical and molecular cytogenetic techniques

• Published in: The Italian journal of zoology Vol. 81; no. 3; pp. 322 - 327
• Main Authors: Rossi, L. F, Chirino, M. G, Luaces, J. P, Merani, M. S
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 03.07.2014
• Subjects: acrocentric chromosomes; adults; anteaters; Armadillo; autosomes; banding pattern; Chromosome; chromosome banding; chromosome number; complement; Dasypodidae; females; fluorescence; fluorescence in situ hybridization; haploidy; heterochromatin; karyotyping; lymphocyte cultures; lymphocytes; males; Myrmecophaga tridactyla; Myrmecophagidae; nucleic acids; pachytene stage; submetacentric chromosomes; telomeres; X chromosome; Xenarthra; Y chromosome
• ISSN: 1748-5851; 1125-0003; 1748-5851
• DOI: 10.1080/11250003.2014.943308

The karyotype of the giant anteater Myrmecophaga tridactyla was studied throughout the species’ Argentine range. Images of the chromosome complement clearly revealed the karyotype and identified previously misinterpreted chromosomes. The peripheral blood lymphocytes of 26 adult animals (11 males and 15 females) were cultured and used to obtain mitotic metaphases. These preparations were subjected to conventional staining, G- and C-banding, and Fluorescent in situ Hibridization (FISH). Spermatocyte pachytene microspreads for one adult were examined for synaptonemal complexes. The karyotype (2n = 60 XX/XY; Fundamental Number (FN) = 110 without XY) showed an autosomal complement of six metacentric, 18 submetacentric, and six acrocentric chromosome pairs. The X chromosome (4.67 ± 0.29% of the haploid set) was shown to be large and submetacentric, similar in size to autosomes 3–5. The Y chromosome was submetacentric (2.60 ± 1.08% of the haploid set). It is, however, larger than the Y chromosome of the closely related armadillos. Pairs 1, 3, 4, 5, 6, 9, 11, 14, 15, 23, 25 and 29 showed small masses of heterochromatin in the pericentromeric region. These masses were slightly larger in chromosome pairs 8, 10 and 18. Pairs 2, 7, 16, 17, 19, 20, 21, 22, 24, 26, 27 and 28 were entirely C-negative. Analysis of the telomeric sequences by FISH involving a Cy3-conjugated peptide nucleic acid pantelomeric probe revealed no signals from the interstitial regions. Ag-NORs were located on chromosomes 5, 10, 11, 21 and 23. The spermatocyte pachytene microspreads confirmed the morphology and size of both sex chromosomes. The present results, obtained via the analysis of a large number of specimens, provide an in-depth characterization of the chromosomal complement of this species.